JPH07100875B2 - Ammonium sulphate-containing etching solution and method of regenerating the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is suitable for regenerating by reoxidation an etchant consisting of an ammoniacal copper tetramine salt contained in an etching liquid under the supply of oxygen and at least a part of the etching liquid. An etching solution containing ammonium sulfate, which is suitable for precipitating an etched metal from an etching solution in an electrolytic cell which is allowed to flow through, and an etching agent comprising an ammoniacal copper tetramine salt contained in the etching solution under the supply of oxygen. It relates to a method for regenerating an ammonium sulphate-containing etching solution by reoxidation and by precipitating the etched metal from the etching solution in an electrolytic cell in which at least a part of the etching solution is allowed to flow through.

Alkaline etching agents, such as ammoniacal copper tetramine salt solutions, are used in the etching of metallic articles, especially in the production of conductor plates, also known by the name of "printed circuits", especially when the conductor plate to be etched is against an acidic etching medium. Used for non-resistive metal parts such as lead, tin or nickel. The reoxidation of the alkaline etching liquid after the etching of the metal is carried out in the presence of oxygen or air with the addition of ammonia gas and / or ammonium salts.

From JP-A-57-73183, a chemical oxidation in the etching liquid is carried out which also promotes the reoxidation of the etching itself, but also of the etching liquid, and thereby renders the remaining solution toxic. It is known to suspend the catalyst particles in an etching solution so that the addition of the agent can be omitted.

In this known method, the etched metal is
It is deposited in the electrolytic cell. On the other hand, only a part of the etching liquid flows through the electrolytic cell. This part can be recycled to the etching chamber as fresh etching liquid after metal deposition and used as rinse liquid for the conductor plate to be cleaned after etching the catalyst particles. In comparison with the advantage of good copper deposition in the electrolytic cell, the disadvantage is that the catalyst particles suspended in the etching solution before entering the electrolytic cell must be separated.

It is also known to etch conductor plates with an ammonium chloride-containing etching solution using an ammoniacal copper complex as an etching agent. If such a solution was introduced into the electrolytic cell for copper deposition, electrolyte decomposition and the generation of unwanted chlorine at the anode would have to be taken into account.

The problem to be solved by the present invention is not only to promote the regeneration of the etching solution without the addition of suspended catalyst particles, but also to the etched copper in the electrolytic cell under the sufficient generation of oxygen at the anode. It is an object of the present invention to provide an ammoniacal etching solution which facilitates the separation of the above-mentioned substances and substantially avoids decomposition of the electrolyte and generation of chlorine at that time.

According to the present invention, the above-mentioned problem is an ammonium sulfate-containing etching solution as described at the beginning of the present specification,
The composition of: [Cu (NH ₃ ) ₄ ] SO ₄ 12 to 30% by weight (NH ₄ ) ₂ SO ₄ 8 to 17% by weight NH ₄ OH 0.7 to 1.1% by weight 0.05 to 0.4% by weight with water balance It is solved by adding% chloride ions.

It has been found that the addition of chloride to the etching solution promotes regeneration, provided that the concentration of chloride ions is adjusted to no higher than 0.4% by weight. With more chloride added, the regeneration rate is reduced to below that of the ammonium sulfate solution with copper tetramine sulphate added as the etching agent. When the chloride ion content becomes much higher, the regeneration is promoted again, at which time the abovementioned disadvantages become more pronounced when ammonium chloride-etching liquids are used.

Favorable results are obtained if the enching solution contains 0.1 to 0.3% by weight of chloride ions.

Next, the method for regenerating an ammonium sulfate-containing etching solution according to the present invention comprises re-oxidizing an etching agent comprising an ammoniacal copper tetramine salt contained in the etching solution under the supply of oxygen, and removing at least a part of the etching solution. In regenerating the ammonium sulfate-containing etching solution by precipitating the etched metal from the etching solution in the electrolytic cell that is allowed to flow through, 0.05 to 0.4% by weight of chlorine ions are added to the etching solution. It is a method for regenerating the above ammonium sulfate-containing etching liquid.

In this regeneration method, the amount of chlorine ion added is 0.05 to 0.4% by weight, but the preferred amount added is 0.1 to 0.
3% by weight.

The invention will now be described in more detail by way of examples with reference to the accompanying drawings.

Example 1 A solution containing 150 g ammonium sulfate and 50 g copper per liter was added by adding gaseous ammonia.
The pH value was adjusted to 9.5. Air was blown in to oxidize the solution. The potential of this solution was measured at room temperature through a platinum rod against a mercury / mercuric oxide reference electrode.

Next, 20 g of copper powder was dissolved in this solution, and as a result,
The potential in the solution dropped by 330 millivolts (mV).
The time course of the potential of the regenerated etching liquid is shown in the curve I of the accompanying drawings. The final potential in the solution is
It reached 260 mV after 60 minutes.

The above etching solution has the following composition: had a _{[Cu (NH 3) 4]} SO 4 15.0 _{wt% (NH 4) 2 SO 4} 12.5 wt% NH ₄ OH to about 1 wt% water balance.

The chloride ion concentration was adjusted variously by adding ammonium chloride. Curves II to V show the regeneration of the etching liquid having a chloride ion concentration of 0.1 to 0.6% by weight in the solution. In the case of 0.1% by weight, the final potential of 280 mV for the solution was already reached after 43 minutes according to curve I, and a slight improvement was still observed at 0.4% by weight of chloride in solution. When using a chlorine ion concentration of 0.6% by weight, the final potential was finally adjusted after 84 minutes.

In addition to ammonium sulphate-containing etching liquids, the invention can also be used in the case of etching liquids containing oxygen-containing anions as well as, for example, etching liquids containing ammonium nitrate or ammonium carbonate.

Example 2 This example was carried out to show that the addition of chloride ions also increases the etching rate obtained with this etching solution. That is, the pH value was adjusted to 9.2 by blowing ammonium with an etching solution containing 150 g of ammonium sulphate per liter and 80 g of copper in the form of copper tetramine sulphate, the pH value was adjusted to 9.2 and was coated with copper at a temperature of 40 ° C. The conductor plate was etched. The average etching rate obtained with this starting solution was 7.8 μm / min. An additional 0.2% by weight in the etching solution is obtained by adding ammonium chloride.
Chloride ions were dissolved. By using this etching liquid, the etching speed could be improved to 11.7 μm / min. By further increasing the concentration of chloride to 0.4% by weight by adding ammonium chloride, the etching rate was still slightly increased. Etching speed is 12.3μ / min at this concentration
It was m.

[Brief description of drawings]

The drawings are charts showing the time course of the potential of the etching liquid with respect to the etching of copper in the etching liquid containing ammonium sulfate according to the present invention.

Front Page Continuation (71) Applicant 999999999 A.L.O.A.T.S.A.H.A.A.M.E.Techhinik Gesellschaft Mit Beschlenktel Haftung, Federal Republic of Germany, Day 7758 Moersburg, Droste Wake, 21 (72) ) Inventor Leander FUJURST Germany, Jülich, Heins Berger Strasse, 10 (72) Inventor Walter Holzell Germany, Meersburg, Droste Wake, 21 (72) Inventor Bertel Castening Germany , Hamburg, Loftenstrasse, 21 (56) References JP-A-48-72026 (JP, A) JP-A-52-88239 (JP, A) JP-B-50-35486 (JP, B2)

Claims (6)

[Claims] 1. An electrolysis suitable for regenerating an etching agent comprising an ammoniacal copper tetramine salt contained in an etching solution under the supply of oxygen by reoxidation, and at least a part of the etching solution is allowed to flow through. An ammonium sulfate-containing etching solution suitable for precipitating an etched metal from an etching solution in a bath, wherein the etching solution contains 0.05 to 0.4% by weight of chlorine ions. 2. An etching solution having the following composition: [Cu (NH ₃ ) ₄ ] SO ₄ 12 to 30 wt% (NH ₄ ) ₂ SO ₄ 8 to 17 wt% NH ₄ OH 0.7 to 1.1 wt% Water balance The etching solution according to claim 1, which has. 3. The etching solution according to claim 1, wherein the etching solution contains chlorine ions in an amount of 0.1 to 0.3% by weight. 4. An etchant comprising an ammoniacal copper tetramine salt contained in the etchant under the supply of oxygen is etched by reoxidation and from an etchant in an electrolytic cell which allows at least a portion of the etchant to flow through. A method for regenerating an ammonium sulfate-containing etching solution by precipitating a metal, wherein 0.05 to 0.4% by weight of chlorine ion is added to the etching solution. 5. The etching solution has the following composition: [Cu (NH ₃ ) ₄ ] SO ₄ 12 to 30 wt% (NH ₄ ) ₂ SO ₄ 8 to 17 wt% NH ₄ OH 0.7 to 1.1 wt% Water balance A method according to claim 4 having. 6. The method according to claim 4, wherein 0.1 to 0.3% by weight of chlorine ions are added to the etching solution.